Use of Uninitialized Variable in Linux kernel - CVE-2026-53243

Vulnerability identifier: #VU135503

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-53243

CWE-ID: CWE-457

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to disclose sensitive information.

The vulnerability exists due to use of an uninitialized variable in rseq_exit_user_update() when updating rseq state for a task. A local user can trigger the vulnerable code path to disclose sensitive information.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-azure (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-ibm (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux-raspi (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1011.11, 7.0.0-1014.14
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1013.13
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18

• https://git.kernel.org/stable/c/6d99479799c69c3cb588fcda19c81d8f61d64ecd
• https://git.kernel.org/stable/c/e12d20a63b61aaf9de4772effccf42cc9a003e58

• Use of Uninitialized Variable in Linux kernel rseq_exit_user_update()
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-azure
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-ibm
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia-7.0